Propylene polymers

ABSTRACT

The present invention relates to a solid catalyst component for the polymerization of olefins CH 2 ═CHR in which R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising Mg, Ti, halogen and an electron donor selected from substituted succinates of a particular formula. Said catalyst components when used in the polymerization of olefins, and in particular of propylene, are capable to give polymers in high yields and with high isotactic index expressed in terms of high xylene insolubility.

The present invention relates to catalyst components for thepolymerization of olefins, to the catalyst obtained therefrom and to theuse of said catalysts in the polymerization of olefins CH₂═CHR in whichR is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms. Inparticular the present invention relates to catalyst components,suitable for the stereospecific polymerization of olefins, comprisingTi, Mg, halogen and an electron donor compound selected from esters ofsubstituted succinic acids (substituted succinates). Said catalystcomponents when used in the polymerization of olefins, and in particularof propylene, are capable to give polymers in high yields and with highisotactic index expressed in terms of high xylene insolubility.

The chemical class of succinates is known in the art. However, thespecific succinates of the present invention have never been used asinternal electron donors in catalysts for the polymerization of olefins.

EP-A-86473 mentions the use of unsubstituted succinates as internaldonors in catalyst components for the polymerization of olefins. The useof diisobutyl succinate and di-n-butyl succinate is also exemplified.The results obtained in terms of isotactic index and yields are howeverpoor.

The use of polycarboxylic acid esters, including succinates, as internaldonors in catalyst components for the polymerization of olefins, is alsogenerically disclosed in EP 125911. Diethyl methylsuccinate and diallylethylsuccinate are mentioned in the description although they are notexemplified. Furthermore, EP263718 mentions, but does not exemplify theuse of diethyl methylsuccinate and di-n-butyl ethylsuccinate as internaldonors. In order to check the performances of these succinates accordingto the teaching of the art the applicant has carried out somepolymerization tests employing catalyst components containing diethylmethylsuccinate and diisobutyl ethylsuccinate, respectively, as internaldonors. As shown in the experimental section, both the so obtainedcatalysts gave an unsatisfactory activity/stereospecificity balance verysimilar to that obtained with catalysts containing unsubstitutedsuccinates.

It has been therefore very surprising to discover that the specificsubstitution in the succinates of the invention generates compoundsthat, when used as internal donors, give catalyst components havingexcellent activity and stereospecificity.

It is therefore an object of the present invention to provide a solidcatalyst component for the polymerization of olefins CH₂═CHR in which Ris hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprisingMg, Ti, halogen and an electron donor selected from succinates offormula (I):

wherein the radicals R₁ and R₂, equal to, or different from, each otherare a C₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl,arylalkyl or alkylaryl group, optionally containing heteroatoms; theradicals R₃ to R₆ equal to, or different from, each other, are hydrogenor a C₁-C₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl,arylalkyl or alkylaryl group, optionally containing heteroatoms, and theradicals R₃ to R₆ which are joined to the same carbon atom can be linkedtogether to form a cycle; with the proviso that when R₃ to R₅ arecontemporaneously hydrogen R₆ is a radical selected from primarybranched, secondary or tertiary alkyl groups, cycloalkyl, aryl,arylalkyl or alkylaryl groups having from 3 to 20 carbon atoms.

R₁ and R₂ are preferably C₁-C₈ alkyl, cycloalkyl, aryl, arylalkyl andalkylaryl groups. Particularly preferred are the compounds in which R₁and R₂ are selected from primary alkyls and in particular branchedprimary alkyls. Examples of suitable R₁ and R₂ groups are methyl, ethyl,n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylhexyl. Particularlypreferred are ethyl, isobutyl, and neopentyl. One of the preferredgroups of compounds described by the formula (I) is that in which R₃ toR₅ are hydrogen and R₆ is a branched alkyl, cycloalkyl, aryl, arylalkyland alkylaryl radical having from 3 to 10 carbon atoms. Particularlypreferred are the compounds in which R₆ is a branched primary alkylgroup or a cycloalkyl group having from 3 to 10 carbon atoms.

Specific examples of suitable monosubstituted succinate compounds arediethyl sec-butylsuccinate, diethyl thexylsuccinate, diethylcyclopropylsuccinate, diethyl norbornylsuccinate, diethyl(10-)perhydronaphthylsuccinate, diethyl trimethylsilylsuccinate, diethylmethoxysuccinate, diethyl p-methoxyphenylsuccinate, diethylp-chlorophenylsuccinate diethyl phenylsuccinate, diethylcyclohexylsuccinate, diethyl benzylsuccinate, diethyl(cyclohexylmethyl)succinate, diethyl t-butylsuccinate, diethylisobutylsuccinate, diethyl isopropylsuccinate, diethylneopentylsuccinate, diethyl isopentylsuccinate, diethyl(1,1,1-trifluoro-2-propyl)succinate, diethyl (9-fluorenyl)succinate,diisobutyl phenylsuccinate, diisobutyl sec-butylsuccinate, diisobutylthexylsuccinate, diisobutyl cyclopropylsuccinate, diisobutyl(2-norbornyl)succinate, diisobutyl (10-)perhydronaphthylsuccinate,diisobutyl trimethylsilylsuccinate, diisobutyl methoxysuccinate,diisobutyl p-methoxyphenylsuccinate, diisobutyl p-chlorophenylsuccinate,diisobutyl cyclohexylsuccinate, diisobutyl benzylsuccinate, diisobutyl(cyclohexylmethyl)succinate, diisobutyl t-butylsuccinate, diisobutylisobutylsuccinate, diisobutyl isopropylsuccinate, diisobutylneopentylsuccinate, diisobutyl isopentylsuccinate, diisobutyl(1,1,1-trifluoro-2-propyl)succinate, diisobutyl (9-fluorenyl)succinate,dineopentyl sec-butylsuccinate, dineopentyl thexylsuccinate, dineopentylcyclopropylsuccinate, dineopentyl (2-norbornyl)succinate, dineopentyl(10-)perhydronaphthylsuccinate, dineopentyl trimethylsilylsuccinate,dineopentyl methoxysuccinate, dineopentyl p-methoxyphenylsuccinate,dineopentyl p-chlorophenylsuccinate, dineopentyl phenylsuccinate,dineopentyl cyclohexylsuccinate, dineopentyl benzylsuccinate,dineopentyl (cyclohexylmethyl)succinate, dineopentyl t-butylsuccinate,dineopentyl isobutylsuccinate, dineopentyl isopropylsuccinate,dineopentyl neopentylsuccinate, dineopentyl isopentylsuccinate,dineopentyl (1,1,1-trifluoro-2-propyl)succinate, dineopentyl(9-fluorenyl)succinate.

Another preferred group of compounds within those of formula (I) is thatin which at least two radicals from R₃ to R₆ are different from hydrogenand are selected from C₁-C₂₀ linear or branched alkyl, alkenyl,cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containingheteroatoms. Particularly preferred are the compounds in which the tworadicals different from hydrogen are linked to the same carbon atom.Specific examples of suitable 2,2-disubstituted succinates are: diethyl2,2-dimethylsuccinate, diethyl 2-ethyl-2-methylsuccinate, diethyl2-benzyl-2-isopropylsuccinate, diethyl2-(cyclohexylmethyl)-2-isobutylsuccinate, diethyl2-cyclopentyl-2-n-propylsuccinate, diethyl 2,2-diisobutylsuccinate,diethyl 2-cyclohexyl-2-ethylsuccinate, diethyl2-isopropyl-2-methylsuccinate, diethyl 2,2-diisopropyl diethyl2-isobutyl-2-ethylsuccinate, diethyl2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, diethyl2-isopentyl-2-isobutylsuccinate, diethyl 2-phenyl-2-n-butylsuccinate,diisobutyl 2,2-dimethylsuccinate, diisobutyl 2-ethyl-2-methylsuccinate,diisobutyl 2-benzyl-2-isopropylsuccinate, diisobutyl2-(cyclohexylmethyl)-2-isobutylsuccinate, diisobutyl2-cyclopentyl-2-n-propylsuccinate, diisobutyl 2,2-diisobutylsuccinate,diisobutyl 2-cyclohexyl-2-ethylsuccinate, diisobutyl2-isopropyl-2-methylsuccinate, diisobutyl 2-isobutyl-2-ethylsuccinate,diisobutyl 2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, diisobutyl2-isopentyl-2-isobutylsuccinate, diisobutyl 2,2-diisopropylsuccinate,diisobutyl 2-phenyl-2-n-propylsuccinate, dineopentyl2,2-dimethylsuccinate, dineopentyl 2-ethyl-2-methylsuccinate,dineopentyl 2-benzyl-2-isopropylsuccinate, dineopentyl2-(cyclohexylmethyl)-2-isobutylsuccinate, dineopentyl2-cyclopentyl-2-n-propylsuccinate, dineopentyl 2,2-diisobutylsuccinate,dineopentyl 2-cyclohexyl-2-ethylsuccinate, dineopentyl2-isopropyl-2-methylsuccinate, dineopentyl 2-isobutyl-2-ethylsuccinate,dineopentyl 2-(1,1,1-trifluoro-2-propyl)-2-methylsuccinate, dineopentyl2,2-diisopropylsuccinate, dineopentyl 2-isopentyl-2-isobutylsuccinate,dineopentyl 2-phenyl-2-n-butylsuccinate.

Furthermore, also the compounds in which at least two radicals differentfrom hydrogen are linked to different carbon atoms, that is R₃ and R₅ orR₆ are particularly preferred. Specific examples of suitable compoundsare: diethyl 2,3-bis(trimethylsilyl)succinate, diethyl2,2-sec-butyl-3-methylsuccinate, diethyl2-(3,3,3-trifluoropropyl)-3-methylsuccinate, diethyl2,3-bis(2-ethylbutyl)succinate, diethyl2,3-diethyl-2-isopropylsuccinate, diethyl2,3-diisopropyl-2-methylsuccinate, diethyl2,3-dicyclohexyl-2-methylsuccinate, diethyl 2,3-dibenzylsuccinate,diethyl 2,3-diisopropylsuccinate, diethyl2,3-bis(cyclohexylmethyl)succinate, diethyl 2,3-di-t-butylsuccinate,diethyl 2,3-diisobutylsuccinate, diethyl 2,3-dineopentylsuccinate,diethyl 2,3-diisopentylsuccinate, diethyl2,3-(1-trifluoromethyl-ethyl)succinate, diethyl2,3-(9-fluorenyl)succinate, diethyl 2-isopropyl-3-isobutylsuccinate,diethyl 2-t-butyl-3-isopropylsuccinate, diethyl2-isopropyl-3-cyclohexylsuccinate, diethyl2-isopentyl-3-cyclohexylsuccinate, diethyl2-cyclohexyl-3-cyclopentylsuccinate, diethyl2,2,3,3-tetramethylsuccinate, diethyl 2,2,3,3-tetraethylsuccinate,diethyl 2,2,3,3-tetrapropylsuccinate, diethyl2,3-diethyl-2,3-diisopropylsuccinate, diisobutyl2,3-bis(trimethylsilyl)succinate, diisobutyl2,2-sec-butyl-3-methylsuccinate, diisobutyl2-(3,3,3-trifluoropropyl)-3-methylsuccinate, diisobutyl2,3-bis(2-ethylbutyl)succinate, diisobutyl2,3-diethyl-2-isopropylsuccinate, diisobutyl2,3-diisopropyl-2-methylsuccinate, diisobutyl2,3-dicyclohexyl-2-methylsuccinate, diisobutyl 2,3-dibenzylsuccinate,diisobutyl 2,3-diisopropylsuccinate, diisobutyl2,3-bis(cyclohexylmethyl)succinate, diisobutyl 2,3-di-t-butylsuccinate,diisobutyl 2,3-diisobutylsuccinate, diisobutyl 2,3-dineopentylsuccinate,diisobutyl 2,3-diisopentylsuccinate, diisobutyl2,3-(1,1,1-trifluoro-2-propyl)succinate, diisobutyl2,3-n-propylsuccinate, diisobutyl 2,3-(9-fluorenyl)succinate, diisobutyl2-isopropyl-3-ibutylsuccinate, diisobutyl 2-terbutyl-3-ipropylsuccinate,diisobutyl 2-isopropyl-3-cyclohexylsuccinate, diisobutyl2-isopentyl-3-cyclohexylsuccinate, diisobutyl2-n-propyl-3-(cyclohexylmethyl)succinate, diisobutyl2-cyclohexyl-3-cyclopentylsuccinate, diisobutyl2,2,3,3-tetramethylsuccinate, diisobutyl 2,2,3,3-tetraethylsuccinate,diisobutyl 2,2,3,3-tetrapropylsuccinate, diisobutyl2,3-diethyl-2,3-diisopropylsuccinate, dineopentyl2,3-bis(trimethylsilyl)succinate, dineopentyl2,2-di-sec-butyl-3-methylsuccinate, dineopentyl2-(3,3,3-trifluoropropyl)-3-methylsuccinate, dineopentyl 2,3bis(2-ethylbutyl)succinate, dineopentyl2,3-diethyl-2-isopropylsuccinate, dineopentyl2,3-diisopropyl-2-methylsuccinate, dineopentyl2,3-dicyclohexyl-2-methylsuccinate, dineopentyl 2,3-dibenzylsuccinate,dineopentyl 2,3-diisopropylsuccinate, dineopentyl2,3-bis(cyclohexylmethyl)succinate, dineopentyl 2,3-di-t-butylsuccinate,dineopentyl 2,3-diisobutylsuccinate, dineopentyl2,3-dineopentylsuccinate, dineopentyl 2,3-diisopentylsuccinate,dineopentyl 2,3-(1,1,1-trifluoro-2-propyl)succinate, dineopentyl2,3-n-propylsuccinate, dineopentyl 2,3(9-fluorenyl)succinate,dineopentyl 2-isopropyl-3-isobutylsuccinate, dineopentyl2-t-butyl-3-isopropylsuccinate, dineopentyl2-isopropyl-3-cyclohexylsuccinate, dineopentyl2-isopentyl-3-cyclohexylsuccinate, dineopentyl2-n-propyl-3-(cyclohexylmethyl)succinate, dineopentyl2-cyclohexyl-3-cyclopentylsuccinate, dineopentyl2,2,3,3-tetramethylsuccinate, dineopentyl 2,2,3,3-tetraethylsuccinate,dineopentyl 2,2,3,3-tetrapropylsuccinate, dineopentyl2,3-diethyl-2,3-diisopropylsuccinate.

As mentioned above the compounds according to formula (I) in which twoor four of the radicals R₃ to R₆ which are joined to the same carbonatom are linked together to form a cycle are also preferred.

Specific examples of suitable compounds are1-(ethoxycarbonyl)-1-(ethoxyacetyl)-2,6-dimethylcyclohexane,1-(ethoxycarbonyl)-1-(ethoxyacetyl)-2,5-dimethylcyclopentane,1-(ethoxycarbonyl)-1-(ethoxyacetylmethyl)-2-methylcyclohexane,1-(ethoxycarbonyl-1-(ethoxy(cyclohexyl)acetyl)cyclohexane.

It is easily derivable for the ones skilled in the art that all theabove mentioned compounds can be used either in form of purestereoisomers or in the form of mixtures of enantiomers, or mixture ofdiastereoisomers and enantiomers. When a pure isomer is to be used it isnormally isolated using the common techniques known in the art. Inparticular some of the succinates of the present invention can be usedas a pure rac or meso forms, or as mixtures thereof, respectively.

As explained above, the catalyst components of the invention comprise,in addition to the above electron donors, Ti, Mg and halogen. Inparticular, the catalyst components comprise a titanium compound, havingat least a Ti-halogen bond and the above mentioned electron donorcompound supported on a Mg halide. The magnesium halide is preferablyMgCl₂ in active form which is widely known from the patent literature asa support for Ziegler-Natta catalysts. Patents U.S. Pat. No. 4,298,718and U.S. Pat. No. 4,495,338 were the first to describe the use of thesecompounds in Ziegler-Natta catalysis. It is known from these patentsthat the magnesium dihalides in active form used as support orco-support in components of catalysts for the polymerization of olefinsare characterized by X-ray spectra in which the most intense diffractionline that appears in the spectrum of the non-active halide is diminishedin intensity and is broadened to form a halo.

The preferred titanium compounds used in the catalyst component of thepresent invention are TiCl₄ and TiCl₃; furthermore, alsoTi-haloalcoholates of formula Ti(OR)_(n-y)X_(y), where n is the valenceof titanium, X is halogen and y is a number between 1 and n, can beused.

The preparation of the solid catalyst component can be carried outaccording to several methods. According to one of these methods, themagnesium dichloride in an anhydrous state and the succinate of formula(I) are milled together under conditions in which activation of themagnesium dichloride occurs. The so obtained product can be treated oneor more times with an excess of TiCl₄ at a temperature between 80 and135° C. This treatment is followed by washings with hydrocarbon solventsuntil chloride ions disappeared. According to a further method, theproduct obtained by co-milling the magnesium chloride in an anhydrousstate, the titanium compound and the β-substituted succinate is treatedwith halogenated hydrocarbons such as 1,2-dichloroethane, chlorobenzene,dichloromethane, etc. The treatment is carried out for a time between 1and 4 hours and at temperature of from 40° C. to the boiling point ofthe halogenated hydrocarbon. The product obtained is then generallywashed with inert hydrocarbon solvents such as hexane.

According to another method, magnesium dichloride is preactivatedaccording to well known methods and then treated with an excess of TiCl₄at a temperature of about 80 to 135° C. which contains, in solution, asuccinate of formula (I). The treatment with TiCl₄ is repeated and thesolid is washed with hexane in order to eliminate any non-reacted TiCl₄.

A further method comprises the reaction between magnesium alcoholates orchloroalcoholates (in particular chloroalcoholates prepared according toU.S. Pat. No. 4,220,554) and an excess of TiCl₄ comprising the succinateof formula (I) in solution at a temperature of about 80 to 120° C.

According to a preferred method, the solid catalyst component can beprepared by reacting a titanium compound of formula Ti(OR)_(n-y)X_(y),where n is the valence of titanium and y is a number between 1 and n,preferably TiCl₄, with a magnesium chloride deriving from an adduct offormula MgCl₂.pROH, where p is a number between 0.1 and 6, preferablyfrom 2 to 3.5, and R is a hydrocarbon radical having 1-18 carbon atoms.The adduct can be suitably prepared in spherical form by mixing alcoholand magnesium chloride in the presence of an inert hydrocarbonimmiscible with the adduct, operating under stirring conditions at themelting temperature of the adduct (100-130° C.). Then, the emulsion isquickly quenched, thereby causing the solidification of the adduct inform of spherical particles. Examples of spherical adducts preparedaccording to this procedure are described in U.S. Pat. Nos. 4,399,054and 4,469,648. The so obtained adduct can be directly reacted with theTi compound or it can be previously subjected to thermally controlleddealcoholation (80-130° C.) so as to obtain an adduct in which thenumber of moles of alcohol is generally lower than 3 preferably between0.1 and 2.5. The reaction with the Ti compound can be carried out bysuspending the adduct (dealcoholated or as such) in cold TiCl₄(generally 0° C.); the mixture is heated up to 80-130° C. and kept atthis temperature for 0.5-2 hours. The treatment with TiCl₄ can becarried out one or more times. The succinate of formula (I) can be addedduring the treatment with TiCl₄. The treatment with the electron donorcompound can be repeated one or more times.

The preparation of catalyst components in spherical form is describedfor example in European Patent Applications EP-A-395083, EP-A-553805,EP-A-553806, EPA-601525 and WO98/44009.

The solid catalyst components obtained according to the above methodshow a surface area (by B.E.T. method) generally between 20 and 500 m²/gand preferably between 50 and 400 m²/g, and a total porosity (by B.E.T.method) higher than 0.2 cm³/g preferably between 0.2 and 0.6 cm³/g. Theporosity (Hg method) due to pores with radius up to 10000 Å generallyranges from 0.3 to 1.5 cm³/g, preferably from 0.45 to 1 cm³/g.

A further method to prepare the solid catalyst component of theinvention comprises halogenating magnesium dihydrocarbyloxide compounds,such as magnesium dialkoxide or diaryloxide, with solution of TiCl₄ inaromatic hydrocarbon (such as toluene, xylene, etc.) at temperaturesbetween 80 and 130° C. The treatment with TiCl₄ in aromatic hydrocarbonsolution can be repeated one or more times, and the β-substitutedsuccinate is added during one or more of these treatments.

In any of these preparation methods the desired succinate of formula (I)can be added as such or, in an alternative way, it can be obtained insitu by using an appropriate precursor capable to be transformed in thedesired electron donor compound by means, for example, of known chemicalreactions such as esterification, transesterification, etc. Generally,the succinate of formula (I) is used in molar ratio with respect to theMgCl₂ of from 0.01 to 1 preferably from 0.05 to 0.5. Moreover, and thisconstitutes another object of the present invention, it has been foundthat interesting results are obtained when others internal electrondonor compounds are used together with the succinates of formula (I).The additional electron donor compound can be the same as the electrondonor (d) disclosed below. In particular very good results have beenobtained when the 1,3-diethers of formula (II) below are used asinternal donors together with a succinate of formula (I).

The solid catalyst components according to the present invention areconverted into catalysts for the polymerization of olefins by reactingthem with organoaluminum compounds according to known methods.

In particular, it is an object of the present invention a catalyst forthe polymerization of olefins CH₂═CHR, in which R is hydrogen or ahydrocarbyl radical with 1-12 carbon atoms, comprising the product ofthe reaction between:

-   -   (a) a solid catalyst component comprising a Mg, Ti and halogen        and an electron donor selected from succinates of formula (I);    -   (b) an alkylaluminum compound and, optionally,    -   (c) one or more electron donor compounds (external donor).

The alkylaluminum compound (b) is preferably selected from the trialkylaluminum compounds such as for example triethylaluminum,triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum. It is also possible to use mixtures oftrialkylaluminum's with alkylaluminum halides, alkylaluminum hydrides oralkylaluminum sesquichlorides such as AlEt₂Cl and Al₂Et₃Cl₃. Alsoalkylalumoxanes can be used.

It is a particular interesting aspect of the invention the fact that theabove described catalysts are able to give polymers with high isotacticindex even when the polymerization is carried out in the absence of anexternal donor (c). In particular, operating for example according tothe working examples described below propylene polymers having anisotactic index around 96% are obtained without using an external donorcompound. These kind of products are very interesting for applicationsin which the crystallinity of the polymer should not be at its maximumlevel. This particular behavior is very surprising in view of the factthat the esters of dicarboxylic acids known in the art, when used asinternal donors, give polymers with a poor isotactic index when thepolymerization is carried out in the absence of an external electrondonor compound.

For applications in which a very high isotactic index is required theuse of an external donor compound is normally advisable. The externaldonor (c) can be of the same type or it can be different from thesuccinate of formula (I). Preferred external electron donor compoundsinclude silicon compounds, ethers, esters, such as ethyl4-ethoxybenzoate, amines, heterocyclic compounds and particularly2,2,6,6-tetramethylpiperidine, ketones and the 1,3-diethers of thegeneral formula (II):

wherein R^(I), R^(II), R^(III), R^(IV), R^(V) and R^(VI) are equal ordifferent to each other, are hydrogen or hydrocarbon radicals havingfrom 1 to 18 carbon atoms, and R^(VII) and R^(VIII), equal or differentfrom each other, have the same meaning of R^(I)-R^(VI) except that theycannot be hydrogen; one or more of the R^(I)-R^(VIII) groups can belinked to form a cycle. Particularly preferred are the 1,3-diethers inwhich R^(VII) and R^(VIII) are selected from C₁-C₄ alkyl radicals,R^(III) and R^(IV) form a condensed unsaturated cycle and R^(I), R^(II),R^(V) and R^(VI) are hydrogen. The use of 9,9-bis(methoxymethyl)fluoreneis particularly preferred.

Another class of preferred external donor compounds is that of siliconcompounds of formula R_(a) ⁷R^(b) ⁸Si(OR⁹)_(c), where a and b areinteger from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c) is4; R⁷, R⁸, and R⁹, are C1-C18 hydrocarbon groups optionally containingheteroatoms. Particularly preferred are the silicon compounds in which ais 1, b is 1, c is 2, at least one of R⁷ and R⁸ is selected frombranched alkyl, alkenyl, alkylene, cycloalkyl or aryl groups with 3-10carbon atoms optionally containing heteroatoms and R⁹ is a C₁-C₁₀ alkylgroup, in particular methyl. Examples of such preferred siliconcompounds are cyclohexylmethyldimethoxysilane, diphenyldimethoxysilane,methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane,2-ethylpiperidinyl-2-t-butyldimethoxysilane and(1,1,1-trifluoro-2-propyl)-2-ethylpiperidinyldimethoxysilane and(1,1,1-trifluoro-2-propyl)-methyldimethoxysilane. Moreover, are alsopreferred the silicon compounds in which a is 0, c is 3, R⁸ is abranched alkyl or cycloalkyl group, optionally containing heteroatoms,and R⁹ is methyl. Examples of such preferred silicon compounds arecyclohexyltrimethoxysilane, t-butyltrimethoxysilane andthexyltrimethoxysilane.

The electron donor compound (c) is used in such an amount to give amolar ratio between the organoaluminum compound and said electron donorcompound (c) of from 0.1 to 500, preferably from 1 to 300 and morepreferably from 3 to 100. As previously indicated, when used in the(co)polymerization of olefins, and in particular of propylene, thecatalysts of the invention allow to obtain, with high yields, polymershaving a high isotactic index (expressed by high xylene insolubilityX.I.), thus showing an excellent balance of properties. This isparticularly surprising in view of the fact that, as it can be seen fromthe comparative examples here below reported, the use as internalelectron donors of α-substituted or unsubstituted succinate compoundsgives worse results in term of yields and/or xylene insolubility.

As mentioned above, the succinates of formula (I) can be used also asexternal donors with good results. In particular, it has been found thatthey are able to give very good results even when they are used asexternal electron donor compounds in combination with catalystcomponents containing an internal donor different from the succinates offormula (I). This is very surprising because the esters of dicarboxylicacids known in the art are normally not able to give satisfactoryresults when used as external donors. On the contrary, the succinates ofthe formula (I) are able to give polymers still having a good balancebetween isotactic index and yields. It is therefore another object ofthe present invention a catalyst system for the polymerization ofolefins CH₂═CHR, in which R is hydrogen or a hydrocarbyl radical with1-12 carbon atoms, comprising the product of the reaction between:

-   -   (i) a solid catalyst component comprising a Mg, Ti and halogen        and an electron donor (d);    -   (ii) an alkylaluminum compound and,    -   (iii) a succinate of formula (I).

The aluminum alkyl compound (ii) has the same meanings of the aluminumcompound (b) given above. The electron donor compound (d) can beselected from ethers, esters of organic mono or bicarboxylic acids, suchas phthalates, benzoates, glutarates, succinates having a differentstructure from those of formula (I), amines. Preferably, it is selectedfrom 1,3-propanediethers of formula (II) and esters of organic mono orbicarboxylic acids in particular phthalates.

As mentioned above all these catalysts can be used in the processes forthe polymerization of olefins CH₂═CHR, in which R is hydrogen or ahydrocarbyl radical with 1-12 carbon atoms. The preferred α-olefins tobe (co)polymerized are ethene, propene, 1-butene, 4-methyl-1-pentene,1-hexene and 1-octene. In particular, the above-described catalysts havebeen used in the (co)polymerization of propene and ethylene to preparedifferent kinds of products. For example the following products can beprepared: high density ethylene polymers (HDPE, having a density higherthan 0.940 g/cm³), comprising ethylene homopolymers and copolymers ofethylene with α-olefins having 3-12 carbon atoms; linear low densitypolyethylenes (LLDPE, having a density lower than 0.940 g/cm³) and verylow density and ultra low density (VLDPE and ULDPE, having a densitylower than 0.920 g/cm³, to 0.880 g/cm³) consisting of copolymers ofethylene with one or more α-olefins having from 3 to 12 carbon atoms,having a mole content of units derived from the ethylene higher than80%; elastomeric copolymers of ethylene and propylene and elastomericterpolymers of ethylene and propylene with smaller proportions of adiene having a content by weight of units derived from the ethylenecomprised between about 30 and 70%, isotactic polypropylenes andcrystalline copolymers of propylene and ethylene and/or other α-olefinshaving a content of units derived from propylene higher than 85% byweight (random copolymers); shock resistant polymers of propyleneobtained by sequential polymerization of propylene and mixtures ofpropylene with ethylene, containing up to 30% by weight of ethylene;copolymers of propylene and 1-butene having a number of units derivedfrom 1-butene comprised between 10 and 40% by weight. Particularlyinteresting are the propylene polymers obtainable with the catalyst ofthe invention showing broad MWD coupled with high isotactic index andhigh modulus. In fact, said polymers having a polydispersity index ofhigher than 5, a content of isotactic units expressed in terms ofpentads of higher than 97% and a flexural modulus of at least 2000 MPa.Preferably, the polydispersity index is higher than 5.1, the flexuralmodulus is higher than 2100 and the percent of propylene units in formof pentads is higher than 97.5%.

Any kind of polymerization process can be used with the catalysts of theinvention that are very versatile. The polymerization can be carried outfor example in slurry using as diluent an inert hydrocarbon solvent, orin bulk using the liquid monomer (for example propylene) as a reactionmedium. Moreover, it is possible to carry out the polymerization processin gas-phase operating in one or more fluidized or mechanically agitatedbed reactors.

The catalyst of the present invention can be used as such in thepolymerization process by introducing it directly into the reactor. Inthe alternative, the catalyst can be pre-polymerized before beingintroduced into the first polymerization reactor. The termpre-polymerized, as used in the art, means a catalyst which has beensubject to a polymerization step at a low conversion degree. Accordingto the present invention a catalyst is considered to be pre-polymerizedwhen the amount the polymer produced is from about 0.1 up to about 1000g per gram of solid catalyst component.

The pre-polymerization can be carried out with the α-olefins selectedfrom the same group of olefins disclosed before. In particular, it isespecially preferred pre-polymerizing ethylene or mixtures thereof withone or more α-olefins in an amount up to 20% by mole. Preferably, theconversion of the pre-polymerized catalyst component is from about 0.2 gup to about 500 g per gram of solid catalyst component.

The pre-polymerization step can be carried out at temperatures from 0 to80° C. preferably from 5 to 50° C. in liquid or gas-phase. Thepre-polymerization step can be performed in-line as a part of acontinuous polymerization process or separately in a batch process. Thebatch pre-polymerization of the catalyst of the invention with ethylenein order to produce an amount of polymer ranging from 0.5 to 20 g pergram of catalyst component is particularly preferred.

The polymerization is generally carried out at temperature of from 20 to120° C., preferably of from 40 to 80° C. When the polymerization iscarried out in gas-phase the operating pressure is generally between 0.5and 10 MPa, preferably between 1 and 5 MPa In the bulk polymerizationthe operating pressure is generally between 1 and 6 MPa preferablybetween 1.5 and 4 MPa Hydrogen or other compounds capable to act aschain transfer agents can be used to control the molecular weight ofpolymer.

The following examples are given in order to better illustrate theinvention without limiting it.

General Procedures and Characterizations

Preparation of Succinates: General Procedures

Succinates can be prepared according to known methods described in theliterature. Descriptive examples of procedures for the synthesis of thesuccinates exemplified in Table 1 are given below.

Alkylation

For literature see for example: N. R. Long and M. W. Rathke, Synth.Commun., 11 (1981) 687; W. G. Kofron and L. G. Wideman, J. Org. Chem.,37 (1972) 555.

Diethyl 2,3-diethyl-2-isopropylsuccinate (ex. 23)

To a mixture of 10 mL (72 mmol) of diisopropylamine in 250 mL oftetrahydrofuran (THF) was added 28.6 mL (72 mmol) of BuLi (2.5 molar incyclohexanes) at −20° C. After 20 minutes stirring, 9.2 g (83% pure)(28.3 mmol) of diethyl 2,3-diethylsuccinate was added at −40° C. andafter addition the mixture was stirred for 2 h at room temperature. Thenthis mixture was cooled to −70° C. and a mixture of 4.3 mL (43 mmol) of2-iodopropane and 7.4 mL (43 mmol) of hexamethylphosphoramide (HMPA) wasadded. After addition the cooling was removed and the mixture wasstirred for four days. The volatiles were removed and 250 mL of etherwas added. The organic layer was washed twice with 100 mL of water. Theorganic layer was isolated, dried over MgSO₄, filtered and concentratedin vacuo yielding an orange oil. This oil was chromatographed oversilica with CH₂Cl₂ yielding 2.3 g (30%) of a 96% pure product. Accordingto gas-chromatography (GC) only one isomer was present.

Oxidative Coupling

For literature see for example: T. J. Brocksom, N. Petragnani, R.Rodrigues and H. La Scala Teixeira, Synthesis, (1975) 396; E. N.Jacobsen, G. E. Totten, G. Wenke, A. C. Karydas, Y. E. Rhodes, Synth.Commun., (1985) 301.

Diethyl 2,3-dipropylsuccinate (ex 18)

To a mixture of 46 mL (0.33 mol) of diisopropylamine in 250 mL of THFwas added 132 mL (0.33 mol) of BuLi (2.5 molar in cyclohexanes) at −20°C. After 20 minutes stirring, 39 g (0.3 mol) of ethyl pentanoate wasadded at −70° C. and after addition the mixture was stirred for 1 h atthis temperature. Then this mixture was added to a mixture of 33 mL(0.30 mol) of TiCl₄ and 200 mL of CH₂Cl₂ at −70° C. keeping thetemperature below −55° C. After addition and subsequently 1 h stirring,the reaction mixture was quenched with 10 mL of water and then thetemperature was slowly raised to room temperature. The volatiles wereremoved and 250 mL of ether was added. The organic layer was washedtwice with 100 mL of water. The organic layer was isolated, dried overMgSO₄, filtered and concentrated in vacuo yielding an orange oil(contained yield was 77%). This oil was distilled which gave twofractions. The best fraction that was obtained was 13.5 g (35%) and 98%pure. The second fraction was 7.5 g and 74% pure.

Reduction

meso Diethyl 2,3-dicyclohexylsuccinate (ex 22)

A stainless-steel autoclave was charged with a mixture of 6.7 g (0.02mol) of meso diethyl 2,3-diphenylsuccinate, 180 mL of isopropanol, and0.23 g of a 5 wt. % Rh/C catalyst. The mixture was hydrogenated for 18 hat 70° C. under a hydrogen pressure of 20 bar. The mixture was filteredover Celite and concentrated under reduced pressure yielding 6.8 g(yield 97%) of 99% pure product.

Esterification

For literature see for example: “Vogel's textbook of practical organicchemistry”, 5^(th) Edition (1989), pages 695-707.

Diethyl 2-phenylsuccinate (ex 1)

A mixture of 50 g of DL-phenylsuccinic acid (0.257 mol), 90 mL (1.59mol) of ethanol, 46 mL of toluene and 0.39 g of concentrated H₂SO₄ washeated to 115° C. An azeotropic mixture of ethanol, toluene and waterwas distilled over a column of 10 cm. When the distillation stopped thesame amounts of ethanol and toluene was added. To obtain a completeconversion this was repeated twice. The resulting oil was distilled at114° C. (2·10⁻² mbar); yield 60.82 g (95%), purity 100% S_(N)2 Coupling

For literature see for example: N. Petragnani and M. Yonashiro,Synthesis, (1980) 710; J. L. Belletire, E. G. Spletzer, and A. R.Pinhas, Tetrahedron Lett., 25 (1984) 5969.

Diisobutyl 2,2,3-trimethylsuccinate (ex 14)

Isobutyric acid (14.6 mL, 157 mmol) was added to a freshly preparedlithium disopropyl amide (LDA) solution (see synthesis of succinate ex23 , 41 mL, 314 mmol of diisopropylamine and 126 mL of BuLi (2.5 M inhexanes; 314 mmol) and 1 L of THF) at 0° C. This mixture was stirred at0° C. for 15 minutes and subsequently for 4 h at 45° C.

Meanwhile in a separate reaction vessel, a mixture of 14.1 mL (157 mmol)of 2-bromopropionic acid and 28 g (157 mmol) of HMPA was added to asuspension of 3.8 g (157 mmol) of NaH in 500 mL of THF at 0° C. whilecontrolling the gas formation. After addition the mixture was stirredfor 15 minutes at 0° C. Then this mixture was added to the mixture ofthe lithium salt of isobutyric acid (described above) at 0° C. Afteraddition the mixture was stirred for 2 h at 35° C. This mixture wasquenched with 150 mL of a NaCl saturated 1 N HCl solution at 0° C. Thismixture was extracted twice with 100 mL of diethyl ether and thecombined ether layers were extracted with 50 mL of a saturated NaClsolution. The organic layer was dried over MgSO₄ and concentrated invacuo yielding a yellow oil. This oil was dissolved in 150 mL ofisobutanol, 100 mL of toluene and 2 mL of concentrated H₂SO₄. Thismixture was heated to reflux with a Dean Stark set-up to remove thewater. After two days the conversion was complete. The reaction mixturewas concentrated in vacuo and the resulting oil was distilled at 155° C.(75 mbar); yield 5.1 g (12%), purity 98%.

Combined Methods

Most of the succinates were prepared by a combination of methodsdescribed above. The different methods used for the synthesis of thesuccinates exemplified in Table 1 are further specified in Table A. Thesequential order in which the methods were used is indicatedalphabetically by a, b and c. TABLE A Succinate (for Methods ofsynthesis type see oxidative S_(N)2 Table 1) Esterification AlkylationReduction coupling coupling  1 A  2 A b  3 A b  4 A  5 A b 12 A 13 A b14 a 15 a B 16 a B c 18 a 22 a b 23 B a 24 B a 25 B a 26 a C b 27 a 30 aPolymerizationPropylene Polymerization: General Procedure

In a 4 liter autoclave, purged with nitrogen flow at 70° C. for one our,75 mL of anhydrous hexane containing 800 mg of AlEt₃, 79.8 mg ofdicyclopentyldimethoxysilane and 10 mg of solid catalyst component wereintroduced in propylene flow at 30° C. The autoclave was closed. 1.5 NLof hydrogen were added and then, under stirring, 1.2 kg of liquidpropene were fed. The temperature was raised to 70° C. in five minutesand the polymerization was carried out at this temperature for twohours. The nonreacted propylene was removed, the polymer was collected,dried at 70° C. under vacuum for three hours, weighed, and fractionatedwith o-xylene to determine the amount of the xylene insoluble (X.I.)fraction at 25° C.

Ethylene/1-butene Polymerization: General Procedure

A 4.0 liter stainless-steel autoclave equipped with a magnetic stirrer,temperature, pressure indicator, feeding line for ethene, propane,1-butene, hydrogen, and a steel vial for the injection of the catalyst,was purified by fluxing pure nitrogen at 70° C. for 60 minutes. It wasthen washed with propane, heated to 75° C. and finally loaded with 800 gof propane, 1-butene (as reported in Table 4), ethene (7.0 bar, partialpressure) and hydrogen (2.0 bar, partial pressure).

In a 100 mL three neck glass flask were introduced in the followingorder, 50 mL of anhydrous hexane, 9.6 mL of 10% by wt/vol, TEAL/hexanesolution, optionally an external donor (E.D., as reported in Table 4)and the solid catalyst. They were mixed together and stirred at roomtemperature for 20 minutes and then introduced in the reactor throughthe steel vial by using a nitrogen overpressure.

Under continuous stirring, the total pressure was maintained constant at75° C. for 120 minutes by feeding ethene. At the end the reactor wasdepressurised and the temperature was dropped to 30° C. The collectedpolymer was dried at 70° C. under a nitrogen flow and weighted.

Determination of Xylene Insolubles (X.I.)

2.5 g of polymer were dissolved in 250 mL of o-xylene under stirring at135° C. for 30 minutes, then the solution was cooled to 25° C. and after30 minutes the insoluble polymer was filtered. The resulting solutionwas evaporated in nitrogen flow and the residue was dried and weighed todetermine the percentage of soluble polymer and then, by difference thexylene insoluble fraction (%).

Determination of Comonomer Content in the Copolymer:

1-Butylene was determined via infrared spectrometry.

Thermal Analysis:

Calorimetric measurements were performed by using a differentialscanning calorimeter DSC Mettler. The instrument is calibrated withindium and tin standards. The weighted sample (5-10 mg), obtained fromthe melt index determination, was sealed into aluminum pans, heated to200° C. and kept at that temperature for a time long enough (5 minutes)to allow a complete melting of all the crystallites. Successively, aftercooling at 20° C./min to −20° C., the peak temperature was assumed ascrystallization temperature (Tc). After standing 5 minutes at 0° C., thesample was heated to 200° C. at a rate of 10° C./min. In this secondheating run, the peak temperature was assumed as melting temperature(Tm) and the area as the global melting enthalpy (ΔH).

Determination of Melt Index (M.I.):

Melt index was measured at 190° C. following ASTM D-1238 over a load of:

-   -   2.16 kg, MI E=MI2.16.    -   21.6 kg, MI F=MI21.6.

The ratio: F/E=MI F/MI E=MI21.6/MI2.16 is then defined as melt flowratio (MFR)

Determination of Density:

Density was determined on the homogenized polymers (from the M.I.determination) by using a gradient column and following the ASTM D-1505procedure.

Determination of Polydispersity Index (P.I.)

This property is strictly connected with the molecular weightdistribution of the polymer under examination. In particular it isinversely proportional to the creep resistance of the polymer in themolten state. Said resistance called modulus separation at low modulusvalue (500 Pa), was determined at a temperature of 200° C. by using aparallel plates rheometer model RMS-800 marketed by RHEOMETRICS (USA),operating at an oscillation frequency which increases from 0.1 rad/secto 100 rad/sec. From the modulus separation value, one can derive theP.I. by way of the equation:P.I.=54.6*(modulus separation)^(−1.76)in which the modulus separation is defined as:modulus separation=frequency at G′=500 Pa/frequency at G″=500 Pawherein G′ is storage modulus and G″ is the loss modulus.

EXAMPLES Examples 1-27 and Comparative Examples 28-30

Preparation of Solid Catalyst Components.

Into a 500 mL four-necked round flask, purged with nitrogen, 250 mL ofTiCl₄ were introduced at 0° C. While stirring, 10.0 g of microspheroidalMgCl₂*2.8C₂H₅OH (prepared according to the method described in ex.2 ofU.S. Pat. No. 4,399,054 but operating at 3000 rpm instead of 10000 rpm)and 7.4 mmol of succinate were added. The temperature was raised to 100°C. and maintained for 120 min. Then, the stirring was discontinued, thesolid product was allowed to settle and the supernatant liquid wassiphoned off. Then 250 mL of fresh TiCl₄ were added. The mixture wasreacted at 120° C. for 60 min and, then, the supernatant liquid wassiphoned off. The solid was washed six times with anhydrous hexane(6×100 mL) at 60° C. Finally, the solid was dried under vacuum andanalyzed. The type and amount of succinate (wt %) and the amount of Ti(wt %) contained in the solid catalyst component are reported inTable 1. Polymerization results are reported in Table 2. The polymerobtained in the example 10 was characterized and it showed apolydispersity index of 6, a content of isotactic units expressed interms of pentads of 98% and a flexural modulus of 2150 MPa. TABLE 1Succinate Ti Ex. no. Type Wt % Wt % 1 Diethyl phenylsuccinate 15.3 4.0 2Diethyl cyclohexylsuccinate 16.4 3.3 3 Diisobutyl cyclohexylsuccinate11.9 3.1 4 Diethyl benzylsuccinate 12.8 2.1 5 Diethylcyclohexylmethylsuccinate 15.3 3.2 6 Diethyl 2,2-dimethylsuccinate 13.02.6 7 Diisobutyl 2,2-dimethylsuccinate 12.1 3.2 8 Diethyl2-ethyl-2-methylsuccinate 13.3 1.9 9 Diisobutyl2-ethyl-2-methylsuccinate 15.2 3.3 10 Diethyl 2,3-diisopropylsuccinate18.9 4.2 11 Diisobutyl 2,3-diisopropylsuccinate 17.2 4.2 12 Diethyl2,3-dibenzylsuccinate 24.1 3.2 13 Diethyl2,3-bis(cyclohexylmethyl)succinate 21.5 4.7 14 Diisobutyl2,2,3-trimethylsuccinate 8.0 4.4 15 Diethyl2-benzyl-3-ethyl-3-methylsuccinate 14.9 3.2 16 Diethyl2-(cyclohexylmethyl)-3-ethyl- 17.9 2.9 3-methylsuccinate 17 Diethylt-butylsuccinate 14.0 2.9 18 Diethyl 2,3-di-n-propylsuccinate 13.1 3.919 Dimethyl 2,3-diisoproylsuccinate 17.7 4.1 20 Diisopropyl2,3-diisopropylsuccinate 13.7 4.3 21 Di-n-butyl 2,3-diisopropylsuccinate17.4 4.6 22 meso Diethyl 2,3-dicyclohexylsuccinate 12.5 4.3 23 Diethyl2,3-diethyl-2-isopropylsuccinate 17.0 4.4 24 Diethyl2,3-diisopropyl-2-methylsuccinate 17.2 5.1 25 Diethyl2,3-diisopropyl-2-ethylsuccinate 12.0 5.4 26 Diethyl2,3-dicyclohexyl-2-methylsuccinate 20.0 5.3 27 Diethyl2,2,3,3-tetramethylsuccinate 9.0 4.0 Comp. 28 Di-n-butyl succinate 7.42.1 Comp. 29 Diethyl methylsuccinate 10.9 3.4 Comp. 30 Diisobutylethylsuccinate 7.7 3.0

TABLE 2 Example Yield X.I. no. kgPP/gCat Wt %  1 20 98.3  2 35 97.4  328 97.3  4 22 96.6  5 33 97.8  6 37 97.2  7 44 97.0  8 44 98.6  9 4297.3 10 61 98.4 11 69 98.8 12 42 96.1 13 39 97.0 14 29 96.6 15 36 96.016 42 96.8 17 25 97.0 18 41 96.7 19 37 98.4 20 40 97.4 21 62 98.5 22 5895.0 23 43 96.2 24 50 94.9 25 40 95.0 26 50 96.0 27 36 95.5 Comp. 28 996.0 Comp. 29 11 95.8 Comp. 30 12 96.0

Example 31

The procedure of examples 1-27 and comparative examples 28-30 was used,but, preparing the solid catalyst component rac diethyl2,3-diisopropylsuccinate was added as succinate. The resulting solidcatalyst component contained: Ti=4.8% by weight, rac diethyl2,3-diisopropylsuccinate 16.8% by weight.

The above mentioned solid catalyst component was polymerized accordingto the general polymerization procedure but without usingdicyclopentyldimethoxysilane. The polymer yield was 65 kg ofpolypropylene/g of solid catalyst component with X.I.=96.1%.

Examples 32-38

The solid catalyst component of example 10 was polymerized according tothe general polymerization procedure but instead ofdicyclopentyldimethoxysilane the electron donors of Table 3 were used.The amount and type of electron donor and the polymerization results arereported in Table 3

Comparative Example 39

The procedure of examples 1-27 and comparative examples 28-30 was used,but, preparing the solid catalyst component, 14 mmol of ethyl benzoatewere added instead of the succinate compound. The resulting solidcatalyst component contained: Ti=3.5% by weight, ethyl benzoate 9.1% byweight.

The above mentioned solid catalyst component was polymerized with thesame procedure of example 38.

The polymerization result is reported in Table 3 TABLE 3 Ex Externaldonor Yield X.I. no. Type mmol kg/g % 32 Cyclohexylmethyldimethoxysilane0.35 61 97.9 33 3,3,3- 0.35 58 96.8 trifluoropropylmethyldimethoxysilane34 3,3,3-trifluoropropyl(2- 0.35 70 98.2 ethylpiperidyl)dimethoxysilane35 Diisopropyldimethoxysilane 0.35 62 97.6 369,9-bis(methoxymethyl)fluorene 0.35 70 98.0 37 Diethyl2,3-diisopropylsuccinate 0.35 59 96.4 38 Ethyl p-ethoxybenzoate 3.00 2098.1 Comp. Ethyl p-ethoxybenzoate 3.00 23 96.1 39

Example 40

The procedure of examples 1-27 and comparative examples 28-30 was used,but, preparing the solid catalyst component 7.4 mmol of diethyl2,3-diisopropylsuccinate and 7.4 mmol of 9,9-bis(methoxymethyl)fluorenewere added.

The resulting solid catalyst component contained: Ti=3.5% by weight,diethyl 2,3-diisopropylsuccinate=11.5% by weight and9,9-bis(methoxymethyl)fluorene=6.9% by weight.

The above mentioned solid catalyst component was polymerized as in thegeneral polymerization procedure. The polymer yield was 74 kg ofpolypropylene/g of solid catalyst component with X.I.=99.3%.

Example 41

The solid catalyst component of example 40 was polymerized according tothe general polymerization procedure but without usingdicyclopentyldimethoxysilane. The polymer yield was 100 kg ofpolypropylene/g of solid catalyst component with X.I.=98.6%.

Example 42

The procedure of examples 1-27 and comparative examples 28-30 was used,but, preparing the solid catalyst component, 7.4 mmol of9,9-bis(methoxymethyl)fluorene were added instead of the succinatecompound. The resulting solid catalyst component contained: Ti=3.5% byweight, 9,9-bis(methoxymethyl)fluorene=18.1% by weight.

The above mentioned solid catalyst component was polymerized accordingto the general polymerization procedure but instead ofdicyclopentyldimethoxysilane, 0.35 mmol of diethyl2,3-diisopropylsuccinate were used. The polymer yield was 84 kg ofpolypropylene/g of solid catalyst component with X.I.=98.6%.

Example 43

Preparation of Solid Catalyst Component

The spherical support, prepared according to the general methoddescribed in Ex. 2 of U.S. Pat. No. 4,399,054 (but operating at 3000 rpminstead of 10000 rpm) was subjected to thermal treatment, under nitrogenflow, within the temperature range of 50-150° C., until sphericalparticles having a residual alcohol content of about 35 wt. % (1.1 molof alcohol per mol of MgCl₂) were obtained.

16 g of this support were charged, under stirring at 0° C., to a 750 mLreactor containing 320 mL of pure TiCl₄. 3.1 mL of diethyl2,3-diisopropylsuccinate, were slowly added and the temperature wasraised to 100° C. in 90 minutes and kept constant for 120 minutes.Stirring was discontinued, settling was allowed to occur and the liquidphase was removed at the temperature of 80° C. Further 320 mL of freshTiCl₄ were added and the temperature was raised to 120° C. and keptconstant for 60 minutes. After 10 minutes settling the liquid phase wasremoved at the temperature of 100° C. The residue was washed withanhydrous heptane (300 mL at 70° C. then 3 times (250 mL each time) thenwith anhydrous hexane at 60° C. The component in spherical form wasvacuum dried at 50° C.

The catalyst composition was as follow: Ti 2.9 wt. % diethyl2,3-diisopropylsuccinate 3.8 wt. % Solvent 13.5 wt. % Ethylene Polymerization:

A 4.0 liter stainless-steel autoclave equipped with a magnetic stirrer,temperature and pressure indicator, feeding line for ethene, propane,hydrogen, and a steel vial for the injection of the catalyst was usedand purified by fluxing pure nitrogen at 70° C. for 60 minutes and thanwashed with propane.

In the following order 50 mL of anhydrous hexane, 5 mL of 10% by wt/vol,TEAL/hexane solution and 0.019 g of the solid catalyst were mixedtogether at room temperature, aged 20 minutes and introduced in theempty reactor in propane flow. The autoclave was closed and 800 g ofpropane were introduced, then the temperature was raised to 75° C. andethylene (7.0 bar, partial pressure) and hydrogen (3.0 bar, partialpressure) were added.

Under continuous stirring, the total pressure was maintained at 75° C.for 180 minutes by feeding ethene. At the end the reactor wasdepressurised and the temperature was dropped to 30° C. The collectedpolymer was dried at 70° C. under a nitrogen flow. 375 g of polyethylenewere collected. The polymer characteristics are reported in Table 5.

Example 44

The solid catalyst of the example 43 was used in the ethylene/1-butenecopolymerization as reported in the general procedure but without usingany external donor.

The other polymerization conditions are reported in Table 4 while thepolymer characteristics are collected in Table 5.

Example 45

The solid catalyst of the example 43 was used in the ethylene/1-butenecopolymerization as reported in the general procedure but by using 0.56mmol of cyclohexylmethyldimethoxysilane as external donor.

The other polymerization conditions are reported in Table 4 while thepolymer characteristics are collected in Table 5.

Example 46

The solid catalyst of the example 43 was used in the ethylene/1-butenecopolymerization as reported in the general procedure but by using 0.56mmol of diethyl 2,3-diisopropylsuccinate as external donor.

The other polymerization conditions are reported in Table 4 while thepolymer characteristics are collected in Table 5.

Example 47

The solid catalyst of the example 43 was used in the ethylene/1-butenecopolymerization in a fluidized gas-phase reactor as described below.

A 15.0 liter stainless-steel fluidized reactor equipped withgas-circulation system, cyclone separator, thermal exchanger,temperature and pressure indicator, feeding line for ethylene, propane,1-butene, hydrogen, and a 1 L steel reactor for the catalystprepolymerization and injection of the prepolymer. The gas-phaseapparatus was purified by fluxing pure nitrogen at 40° C. for 12 hoursand then was circulated a propane (10 bar, partial pressure) mixturecontaining 1.5 g of TEAL at 80° C. for 30 minutes. It was thendepressurized and the reactor washed with pure propane, heated to 75° C.and finally loaded with propane (2 bar partial pressure), 1-butene (asreported in Table 4), ethylene (7.1 bar, partial pressure) and hydrogen(2.1 bar, partial pressure).

In a 100 mL three neck glass flask were introduced in the followingorder, 20 mL of anhydrous hexane, 9.6 mL of 10% by wt/vol, TEAL/hexanesolution and the solid catalyst of the example 43 (in the amountreported in Table 4). They were mixed together and stirred at roomtemperature for 5 minutes and then introduced in the prepolymerizationreactor maintained in a propane flow.

The autoclave was closed and 80 g of propane and 90 g of propene wereintroduced at 40° C. The mixture was allowed stirring at 40° C. for 30minutes. The autoclave was then depressurized to eliminate the excess ofunreacted propene, and the obtained prepolymer was injected into thegas-phase reactor by using a propane overpressure (1 bar increase in thegas-phase reactor). The final pressure, in the fluidized reactor, wasmaintained constant at 75° C. for 180 minutes by feeding a 10 wt. %1-butene/ethene mixture.

At the end, the reactor was depressurised and the temperature wasdropped to 30° C. The collected polymer was dried at 70° C. under anitrogen flow and weighted.

The polymer characteristics are collected in Table 5.

Example 48

Preparation of Solid Catalyst Component

The procedure of example 43 was repeated but instead of diethyl2,3-diisopropylsuccinate was used diisobutyl phthalate (11.8 mmol). Thecharacteristics of the dried catalyst were as follow: Ti 2.3 wt. %diisobutyl phthalate 4.4 wt. % Solvent 5.5 wt. %

The solid catalyst was then used in the ethylene/1-butenecopolymerization as reported in the general procedure but using diethyl2,3-diisopropylsuccinate as E.D.

The other polymerization conditions are reported in Table 4 while thepolymer characteristics are collected in Table 5. TABLE 4 Ethylene(co)polymerization Polymer Catalyst E.D. time Yield Example Mg Type MmolAI/E.D. 1-butene G min g kg/gcat 43 19.0 — — — — 180 375 19.7 44 21.0 —— — 170 120 300 14.3 45 38.8 CHMMS 0.56 15 200 120 470 12.1 46 22.0Diethyl 2,3- 0.56 15 200 120 255 11.6 diisopropyl- succinate 47 46.0 — ——  330* 180 815 17.7 48 39.5 Diethyl 2,3- 0.56 15 200 120 290  7.3diisopropyl- succinateCHMMS = Cyclohexyl-methyl-dimethoxysilane

TABLE 5 Copolymer characterization Melt Index 1-C4- D. S. C. Polymer E F(I.R.) Density Tc Tm X.S. Example dg/min dg/min F/E Wt. % g/mL °C. °C.DH J/g wt. % 43 0.44 13.9 31.6 — — — — — — 44 0.86 26.7 31.5 10.1 0.9174105 124.8 126 14.9 45 1.0 28.1 28.1  9.8 0.9170 105 123.7 125 14.8 460.79 25.8 32.6  8.4 0.9199 n.d. n.d. n.d. n.d. 47 2.3 77.1 33.5 10.50.9136 106 123.9 118 n.d. 48 0.84 29.5 35.1 12.8 0.9165 107 126.0 116n.d.n.d. = not determined

1-38. (canceled).
 39. Propylene polymers characterized in that they have a polydispersity index of higher than 5, a content of isotactic units expressed in terms of pentads of higher than 97% and a flexural modulus of at least 2000 MPa.
 40. The propylene polymers according to claim 39 in which the polydispersity index is higher than 5.1, the flexural modulus is higher than 2100 MPa and the content of isotactic units expressed in terms of pentads is higher than 97.5%. 